The project encompasses studies on the chemical structure of endotoxic lipopolysaccharides and glycolipis, using analytical and instrumental investigations of chromatographically pure preparations. Organic chemical syntheses of model compounds, and the testing of their biological activities in various endotoxic reactions is also part of the research plan. Studies on the relationship of structure to function of endotoxin (or lipopolysaccharide) also include attempts to localize various biological activities in the complex structure of the endotoxin molecule. Major emphasis is placed on the non-specific enhancement of tumor resistance against experimental tumors, and explorations of possible use of endotoxins and their derivatives as immunostimulants in human malignancies. BIBLIOGRAPHIC REFERENCES: Alois Nowotny, Ulrich H. Behling and Helena L. Chang: Relation of structure to function in bacterial endotoxins VIII. Biological activities in a polysaccharide-rich fraction. J. Immunol. 115:199-203, 1975. Ah-Kau Ng, Chen Lo H. Chen, Chung Ming Chang and A. Nowotny: Relationship of structure to function in bacterial endotoxins XI. Serologically cross-reactive components and their effect on protection of mice against some gram-negative infections. J. Gen. Microbiol. (in press) 1976.